Food roasting machines are in wide use. One particularly common roasting machine is utilized to prepare coffee beans to be either packaged or ground and brewed. The roasting process consumes considerable energy and, without some emissions treatment, emits noxious gases. To reduce the emissions, various solutions have been employed such as those that utilize high temperature incineration of the output stream along with costly filtration. The incineration adds to the energy consumption and complexity of the roasting system. In addition, the practice of incineration also often involves installation of costly ventilation systems, which some buildings are unable to accommodate. There is an ongoing need to find better designs that reduce energy consumption and provide a clean output.